(last updated on Jul 2, 2020)

Bangalore weather hardly ever disappoints. Coffee is often paired with dewy, chilly mornings while evening tea is accompanied by Bangalore’s signature showers. To Bangaloreans, who are so accustomed to the familiar scent of evening rain, solar panels might seem unconventional. However, the truth is that solar photovoltaic (PV) systems work better at moderate temperatures.

rooftop solar and metro rail
Solar panels in the backdrop of BMRCL metro

To understand the reason behind this common misconception about solar energy, let’s first understand how solar PV works.

When sunlight hits the solar PV panels, the sun’s energy is converted into electricity, which in turn powers homes, apartments, offices, schools, and more.  Hence, solar panels harness the sun’s light and not its heat. The amount of electricity generated depends on multiple factors:

1. Temperature

2. Wind speed

3. Daily sunlight hours

4. Intensity and angle of sunlight

5. Solar panel type

6. Inverter technology

7. Shading (by obstructions)

Here, we will be focussing on the first three reasons, which are weather dependent and out of our control, in our quest to prove that Bangalore is a great city to build the solar sufficient palace of your dreams! We will provide facts about solar panel energy production and substantiate them with Solarify’s own solar energy generation data.

Fact: “Beyond a particular limit, the efficiency of a solar panel is inversely proportional to its temperature.”

Solar panels operate at a higher temperature than their surroundings because the panel glass traps the heat of the sun, akin to what happens in a greenhouse.

For instance, if the surrounding temperature is 25°C, the solar panel’s temperature is close to 45°C. The power generation efficiency reduces once the panel temperature rises beyond an optimum of 45°C. A 1°C rise in panel temperature leads to a 0.45% decrease in its efficiency. The phenomenon is known as the temperature derating factor.

The power generation efficiency of solar panels generation also depends upon the panel type. For instance, monocrystalline solar panels, apart from their higher efficiency, handle temperature changes better than polycrystalline solar panels.

Fact: “Windy Days improve the efficiency of solar power generation.”

As we have read above, there is a constant exchange of heat taking place between the photovoltaic cell module and its surroundings. Under normal conditions, this difference is maintained at about 25°C. However, when there is a lot of wind, the difference dramatically decreases. Hence, heavy winds can counteract the temperature degrading factor.

In Bangalore, the Summer Months achieve the greatest wind speeds

Source: Windfinder

The proof is in the panels.

Here is an analysis of solar generation data of a 96.2-kilowatt power rooftop solar system installed by us.

Panels | Vikram Solar Polycrystalline 325 Wp
Inverter | SolarEdge inverters and optimisers
Place | Brigade Petunia, Banashankari (apartment complex)

Highlights

First apartment in Bangalore to use solar for 100% of their community area
• Second best performing SolarEdge installation in India

solar generation graph

Solar Generation

Brigade Petunia, Banashankari • 96.2 kW rooftop solar system • Generation data for last 12 months

Let’s break this down into a season-wise analysis of solar power generation from Brigade Petunia (a Solarify project), over the last 12 months.

Bangalore Summer

summer solar generation graph

Summers in Bangalore last from April to June, with April and May being the hottest months of the year. The temperature can reach as high as 33-34°C, causing the panels to hit temperatures exceeding 55°C. As a result, the efficiency of the solar panels is slightly affected in the summer because of the temperature derating factor. Therefore, the generation is low when compared to March, despite receiving a similar duration of sunlight. However, as a whole, the Summer months produce the greatest amount of energy and this can be attributed to longer daily sunlight hours as well as higher wind speeds.

Bangalore Winter

winter solar generation graph

Winters in Bangalore last from December to February, with January being the coldest. Contrary to popular belief, this works excellently for the solar panels. As we can see from the graph, the solar production peaks in January. We experience this because the temperature is closest to the optimal operating temperature of the panels, 45°C. So, as far as Bangalore is concerned – colder the weather, the better.

Bangalore Monsoon

monsoon solar generation graph

Though Bangalore gets intermittent rainfall throughout the year; July, August, and September receive the most rainfall. The amount of energy generated is consistently lower throughout this monsoon season. Solar panels cannot produce as much electricity under cloudy conditions, and their output can reduce to 30% in overcast conditions. The primary reason for this reduction is because of the lower intensity of sunlight due to cloud cover. Despite this reason, the system produces a minimum of 10 MWh of electricity in a month.

So, solar works in Bangalore, huh?

Bangalore is one of the ideal cities in India to go solar in. All-in-all, the moderate temperatures year-round, high wind speeds and availability of 280 days of good sunlight, combine to make Bangalore an excellent place for using solar power.


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